When I upgraded my Fedora 13 to Fedora 14 last night I found the system freezes at many points. For example, I am unable to open terminal while I am browsing through the firefox. I am unable to open Virtualbox with firefox open. My System hangs when I am trying to play "Parole Media Player".
I raised a bug with bugzilla.redhat.com and they suggested to update the kernel to update the kernel to 22.214.171.124-74 kernel that fixes that issue.
Things are pretty working now and it seems like 126.96.36.199-x seems to carry bug.
Browse through Fedora Build System at http://koji.fedoraproject.org/koji/packageinfo?packageID=8 and download the latest kernel. Refer http://linuxscoop.blogspot.com/2010/12/how-to-compile-linux-kernel.html to compile the kernel.
Be aware of this bug and enjoy Fedora Box.